Lysophosphatidylethanolamine naturally exists in cells of plants and animals, and is particularly much contained in yolks or brain cells. The lysophosphatidylethanolamine is derived from phosphatidylethanolamine which is a kind of phospholipids found in a cell membrane. The phosphatidylethanolamine plentiful in the yolk or soybean lecithin is a kind of the phospholipids and contains two fatty acids in a molecule thereof. In a living body, the phosphatidylethanolamine is subject to an action of phospholipase A2 action, which is hydrolase of the phospholipids, so that one fatty acid located at a sn-2 position is removed. As a result, the phosphatidylethanolamine is converted into lysophosphatidylethanolamine.
The lysophosphatidylethanolamine is known that it plays an important role in ripening and senescence of fruits. It is known that treatment of the lysophosphatidylethanolamine suppresses the ripening of leaves of a tomato and the fruit. In addition, it is also known that the treatment of lysophosphatidylethanolamine after the harvest of tomato extends a storage period of the fruit (U.S. Pat. Nos. 5,110,341 and 5,126,155). Further, it is also known that the treatment of the lysophosphatidylethanolamine to apples promotes formation of anthocyanine in the skin and suppresses loss of firmness during the storage of the apples harvested. It is known that these actions are related to functions of lowering a respiration rate of the fruit such as apple, cranberry and tomato and promoting or suppressing a formation of ethylene gas (Farag, K. M. and J. P. Palta, “Stimulation of Ethylene Production by Erea, Thidiazoron, and Lysophosphatidylethanolamine and Possible sites of this stimulation” Annual meeting of the American Society of Plant Physiologists, April 1989).
A solution of lysophosphatidylethanolamine which is adjusted to have a proper concentration is used as means for prolonging a lifetime of a cut flower (HortScience 32(5): 888-890, 1997). In general, since treatment of a silver thiosulfate solution containing sugar to a harvested flower about for 20 hours or more suppresses the senescence of the flower, it has been used for such uses up to recently. However, since silver ions contained in the solution cause environmental pollutions, the use of the solution is avoided in U.S recently. The lysophosphatidylethanolamine which is purified from nature sources is known to improve the storage ability of the cut flower in a vase, as the sliver thiosulfate solution. Accordingly, it is actively driven the use of the lysophosphatidylethanolamine in the related fields.
As described above, the lysophosphatidylethanolamine is very usefully used in an agriculture field. However, it is difficult to keep and maintain the stable formulation thereof in an aqueous solution. In case of a 10% aqueous solution of lysophosphatidylethanolamine, which is currently commercialized, there occurs precipitation at temperatures below about 20° C., so that the formulation thereof becomes unstable. In addition, when it is kept for a long time, there occurs precipitation. Further, when the lysophosphatidylethanolamine is diluted in water just before it is applied to the crops, since it is not stably dissolved, it cannot be effectively used. Additionally, there occurs a problem in the external appearance thereof as a product when it is put on the market.